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Knowing that I have hands


To: Ruy R.
From: Geoffrey Klempner
Subject: Knowing that I have hands
Date: 26th February 2010 14:01

Dear Ruy,

Thank you for your email of 16 February, with your essay for the University of London BA Epistemology module, in response to the question, 'Must one have independent grounds for thinking that one has hands in order to know that one has hands? If not, explain why not. If so, explain the consequences for one's belief that one has hands.'

Your essay is rather concise, although it covers the main issue -- externalism vs internalism in the theory of knowledge, and also briefly alludes to Nozick's externalist theory of knowledge as 'tracking the truth'.

In terms of length, if you could do something like his in a one hour examination, that would be acceptable, although at a mere 706 words it is on the short side. I have students who have sent me up to 1600 words written in one hour, although I doubt whether I could do this!

My task is to respond to what you write rather than to write your essay for you. However, there are some important things to say about this question which you need to know.

The example, 'I have two hands' originally comes from a famous 1939 paper by G.E. Moore 'Proof of an External World'.

Moore's argument is the perfect mirror-image of the brain in a vat argument which you give, as an argument for scepticism, given an internalist starting point. According to the brain in a vat argument:

1. It is not the case that I know that I am not brain in a vat.

2. If I know that I have two hands then I know that I am not a brain in a vat.

3. Therefore, I do not know that I have two hands (by Modus Tolens).

G.E. Moore's argument goes:

1. I know that I have two hands.

2. If it is not the case that I know that I am not a brain in a vat then I do not know that I have two hands.

3. Therefore, it is the case that I know that I am not a brain in a vat (by Modus Tolens and two applications of double negation).

Wittgenstein's book 'On Certainty' was inspired to a considerable extent by Moore's argument. It is one of his best books (the very last that he wrote before he died) and well worth reading.

In 'Philosophical Investigations' Wittgenstein says something very pertinent about Moore. He imagines an objector saying, 'But, if you are *certain*, isn't it that you are shutting your eyes in face of doubt?' Wittgenstein's reply: 'They are shut' (p.224).

The idea that one is merely 'shutting one's eyes to doubt' is very difficult to resist, in a case like Moore's 'I have two hands'. How can Moore be so certain? Is it ignorance of all the science fiction possibilities? Has God told him that he has two hands?

What the objector wants to say is, 'I can *see* the possibility of a brain in a vat, and because I can see that possibility, I cannot say, categorically, that I know that I have two hands. In order to know that I have two hands I would have to be in a position to rule out the brain in a vat scenario. But that is something I cannot do!'

Wittgenstein's response catches the objector off guard. To merely 'describe a possibility' or 'see a possibility' is not the same as 'entertaining a doubt'. To imagine a doubt is not to doubt. For example, I can imagine that as I write these words, a hole has opened up just behind me. If I were to get up now and walk to the door of my office, I would fall down the hole and find myself in Wonderland. What I have described is logically possible, just as the brain in a vat scenario is logically possible. Is that a reason to glance down as I get up from my chair, in order to verify that the hole isn't there?

But every single move I make 'assumes' things that are not the case. As I raise my mug of coffee to my lips I assume hat the coffee hasn't turned to poison. And so on.

What I have described here is the beginnings of an *internalist* argument against scepticism. It's easy to go the externalist route. The problem (which most philosophers taking the external option too easily ignore) is that first step, where one gives up the first-person perspective. How can I give this up? How can I shut my eyes to doubt?

They are shut, because the very idea of 'keeping my eyes open' leads to absurdity. I cannot make a single move. I cannot bat an eyelid (my eyelashes might have turned into Semtex explosive which will detonate the moment they touch).

The sceptic who says, 'I do not know that I have two hands', is using words which have no meaning. It is not just that he is 'using the term 'know' in a different way from the way we normally use the word 'know'', which would be the objection from 'ordinary language philosophy'. The problem with arguments from ordinary language is that sometimes ordinary language can be wrong, can incorporate false philosophical beliefs or theories. But that's not what Wittgenstein is saying. What he is saying (in effect) is that someone who says, 'I do not know that I have two hands' might as well be saying, 'I do not ba-ba-ba-ba that I have two hands.' If you tell me that you don't know that you have two hands, then I don't know what you mean by 'know'.

I said I wasn't going to write your essay for you. I would guess that the examiner is not expecting a critique of Moore and Wittgenstein, even though the example of hands might look like a very strong hint. This just isn't what most epistemologists discuss these days. Which is a pity!

So far as the question is concerned, I guess that one thing the examiner is looking for is a discussion of, e.g. foundationalism and coherentism, as providing grounds for every proposition I believe. Foundationalism can only do this if there are some propositions which are indubitable, such as 'I see a red patch in my visual field now'. Coherentism offers a quasi-independent ground (because all my beliefs are ultimately in the same boat, each supported by all the others. As internalist strategies both have fatal weaknesses. Whereas the 'my eyes are shut' argument, I would argue, gets to the root of the problem.

All the best,